The best open source alternative to Concepts is Inkscape. If that doesn't suit you, our users have ranked more than 25 alternatives to Concepts and 13 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Concepts are Krita, Xournal++, Linwood Butterfly and Rnote.
Open source vector graphics editor with SVG support. Offers tablet support, non-destructive editing, and live previews. No registration needed, works offline, extensible with plugins, and provides privacy-focused, ad-free experience across multiple platforms.
Free, open-source painting software designed by artists for artists. Offers customizable UI, 9 brush engines, color management, tablet support, non-destructive editing, and privacy features. Portable and available on major platforms, supporting seamless texture creation.
Handwritten note-taking and PDF annotation using pen input and pressure sensitivity, shape drawing, customizable toolbar layouts, image insertion, audio recording, multi-language options, LaTeX integration, and complete export in PDF or PNG formats across all platforms.
Butterfly is a note-taking app where your ideas come first. You can paint, add texts, and export them easily on every device. This app works on android, windows, linux, and in the web.
Rnote aims to be a simple but functional note taking application for freehand drawing or annotating pictures or documents. It eventually should be able to import / export various media file formats.
A (work-in-progress) cross-platform libre notes app. Please note that this app is still in early stages and not ready to trust with your notes yet.
Lorien is an infinite canvas drawing/note-taking app that is focused on performance, small savefiles and simplicity. It's not based on bitmap images like Krita, Gimp or Photoshop; it rather saves brush strokes as a collection of points and renders them at runtime (kind of...
Xournal is an application for notetaking, sketching, keeping a journal using a stylus. It is free software (GNU GPL) and runs on Linux (recent distributions), Windows and other GTK+/Gnome platforms.
HelixNotes is a local markdown note-taking app built with Rust, Tauri 2.0, and SvelteKit. Your notes are standard .md files on your filesystem - sync with whatever you want or nothing at all.
Write is a word processor for handwriting, designed primarily for tablets with an active stylus. Write has the functionality of a vector drawing application, plus a unique set of tools which ease the editing of handwritten text.
SpeedyNote is a fast, open-source note-taking application designed for stylus users who need iPad-quality annotation on budget hardware. Built with native C++ and Qt, it delivers 360Hz stylus input on hardware as modest as an Intel Celeron N4000 at 1.
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There's a paywall for exporting it in SVG, PNG, PDF.
In Xournal++, you can increase the canvas size to any size you want. It is not unlimited size, but you can export it as a PDF, PNG, or even SVG.